1. Field of the Invention
The invention relates to ventilation systems and interconnections of elements thereof, and more particularly, to interconnection elements interposed between pipes and pipe interconnection structures.
2. Description of Related Art
Historically, heating, air conditioning and other environment "controlling" devices employing fuels require ventilation systems for safely disposing of smoke, fumes and other residue gases. As a result of the chemical composition of the residue gases, many ventilation systems operate in relatively severe environments, and are subjected to physical/chemical phenomena which subsequently cause damage, such as pitting and corrosion. Accordingly, a substantial amount of technical research and development has been ongoing with respect to ventilation system design.
The structure and integrity of ventilation systems has become of even greater import during the last several years in view of the increasing use of higher efficient environment controlling appliances, such as high efficient furnaces. Continuously rising energy costs have created a large market demand for such appliances. However, such high efficiency devices place relatively greater demands on appliance ventilation systems.
For example, because high efficiency appliances actually utilize relatively more of the energy which they produce, less energy escapes through the ventilation systems. Accordingly, such ventilation systems will have relatively lower flue gas temperatures within the systems. With lower flue gas temperatures, condensation may occur. The moisture produced by the condensation, along with acidic residue from the flue gases, can produce a potentially damaging acidic condensate. For ventilation systems comprising metal elements, this acidic condensate can rapidly produce severe pitting and corrosion.
In view of problems such as the foregoing with respect to metal ventilation pipes and fittings, alternative materials have been employed. For example, polyvinylchloride (PVC) has been utilized as an alternative to metal materials. However, PVC materials have the potential of producing toxic fumes when exposed to open flames, such as may result in the event of the occurrence of a house fire. Also, although PVC materials can be employed for heating appliances having efficiencies over 90 percent, PVC materials per se cannot withstand the flue gas temperatures typically produced by heating appliances having an efficiency in the range of 80 percent to 90 percent.
A substantial advance in the state of the art with respect to ventilation systems for high efficient gas heating appliances appears to be provided by a ventilation system developed by Hart & Cooley, and marketed under the trademark ULTRAVENT.RTM.. This system employs a relatively new resin marketed by G.E. Plastics, and comprising a high-temperature engineering thermoplastic. The resin appears to have a high resistivity to relatively high temperatures and corrosion. The resin also appears to provide substantive protection against condensation and acidity in ventilation system applications. Also, the resin does not support combustion or the production of toxic fumes, even when the resin is exposed to direct flames. For purposes of disposing of condensation, the ULTRAVENT.RTM. ventilation system also provides for the use of a condensate discharge fitting, which collects potentially corrosive condensation and drains the same out of the ventilation system.
The ULTRAVENT.RTM. ventilation system and other venting systems advantageously accommodate positive pressure within the pipes and fittings of the systems. However, to provide for accommodation of positive pressure, and to ensure against the leakage of flue gases, interconnections of pipes and fittings within the systems must be properly sealed.
Various means are known for interconnecting pipes and pipe fittings of ventilation systems. For systems accommodating positive pressure, it is known to employ sealants which are applied to pipes and pipe fitting joints while they are in a semi-fluidic state. The sealants then harden or "set up" so as to provide an appropriate seal. For ventilation system materials such as PVC or other solvent-bond materials, a number of known sealants are available which set up relatively quickly after application. However, for certain types of materials, the only known sealants which provide for a relatively quick set-up may be toxic and inappropriate for use in residential and commercial establishments.
Other types of sealants appropriate for providing pressure and leakage seals may take somewhat longer to set up. During the period of time that the sealant is curing, it is possible that the pipe and pipe fitting joints may accidently disengage or become misaligned. For example, in relatively complex or large ventilation systems, a substantial number of pipe and pipe fitting joints may be assembled. With such systems, accidental disengagement or misalignment of one joint while the assembler is working on another joint may readily occur, particularly if the sealants are relatively early in their cure periods. Also, even when the sealants cure, and provide both an adhesive and a mechanical joint, accidental disengagement is a possibility.
It is known to employ various types of structural elements for interconnecting pipes and pipe fittings, both within the ventilation system industry and otherwise. For example, Durkin, U.S. Pat. No. 4,865,674 issued Sept. 12, 1989 discloses a method and apparatus for interconnecting thermoplastic pipes.
More specifically, Durkin discloses the use of an interconnecting sleeve made from a strip of relatively thin spring steel. The strip of spring steel is initially stamped to a configuration as shown in FIG. 2 of the Durkin patent. A series of barbs are formed integrally within the stamping, and are alternately bent plus or minus 45.degree. from the stamping thickness. The spring steel strip is further formed so as to provide for a series of three parallel circuit paths, with the paths being approximately equal in length and resistance. The spring steel strip is also formed with a pair of terminals at opposing ends of the strip. After construction, the sleeve is cylindrically rolled to a desired diameter. A staggered or serpentine seam is provided along each lateral edge, so that no electrical contact is made completely along the sleeve circumference. With the stamping rolled to the cylindrical configuration, the terminals are projected radially outward so that a voltage can be applied to the seam, for purposes of providing a parallel current flow through the sleeve.
As the sleeve is rolled into a cylinder, the barbs are positioned so as to extend toward inside and outside diameters. The barbs are compressed toward the stamping thickness as a pipe is inserted in the inside diameter of the sleeve, and as a fitting or second pipe is mounted on the outside diameter.
With the sleeve and pipes appropriately positioned, a voltage is applied to the terminals of the sleeve. As current flows through the parallel paths of the sleeve, heat is generated which causes the plastic from the pipes to melt. As the plastic melts, the compressed barbs will begin to move toward their "relaxed" positions. Such movement will displace plastic along the barbs' paths, and the displaced plastic will move into openings in the stamping, joining with plastic displaced by other barbs. After the voltage is removed from the sleeve, the plastic will again harden, thereby sealing and encasing the spring steel insert.
The barbs are defined as providing a clamping or immobilizing action during initial assembly, so as to prevent pipe separation or movement once the assembly is achieved. Although the barbs project radially relative to the sleeve, their lengths extend axially of the pipes. In this manner, assembly is facilitated while retaining immobilization.
Other types of arrangements for interconnecting pipes, pipe fittings and various types of tubes are also known. For example, Goldstein, U.S. Pat. No. 3,249,373 issued May 3, 1966, discloses a tube coupling employing a longitudinally movable biting ring. The coupling arrangement is disclosed as being employed in a system utilizing two lengths of tubing, with a first tube being sufficiently larger in internal diameter than the second tube, so as to permit telescopic entry of the second tube into the first tube.
The Goldstein arrangement utilizes a pair of annular bands glued or otherwise affixed to the interior of the larger first tube, and arranged in an axially spaced-apart relationship. One of the bands is positioned adjacent to one end of the tube, while the other band is positioned a suitable distance inwardly of the tube. The bands are employed as abutment stops for the tube coupling device, with the device being longitudinally slidably movable within the first tube between the bands.
The coupling device itself comprises a relatively thin onepiece ring consisting of sheet metal. One peripheral edge of the ring is bent rearwardly upon itself, so as to extend into the ring and provide a double-thickness portion for purposes of reinforcement. A set of teeth or prongs are formed at the periphery of the thickened portion of the edge, and are arranged in a circumferential manner. The teeth extend toward the other end of the ring, and are bent so as to extend at an angle, thereby projecting radially inwardly of the formed annulus. The external diameter of the ring is such that it can slidably move, without interference within the larger first tube, between the bands until the ring abuts one or the other of the bands, depending upon the direction of longitudinal travel.
The diameters of the tubes are formed such that the smaller second tube will enter the larger first tube and initially slidably engage the bands, with the bands serving so as to center and guide the second tube. The second tube is longitudinally or axially advanced into the larger tube until the forward end of the second tube engages the coupling ring. Continuing advancement of the second tube will actuate the coupling ring, with the advancing movement continuing until the coupling ring abuts the innermost band. Further advancement of the second tube will cause the teeth of the coupling ring to be flexed against the inner peripheral bounding surface of the ring, thereby substantially flattening the teeth. Any withdrawing movement of the tubes for purposes of separation will carry the ring with the moving tube until the ring abuts an end band, which prevents further retraction of the ring. The teeth are thereby bent into the tube and substantially gouged into the peripheral surface of the tube. Any further withdrawing movement of the second tube will cause even deeper penetration of the teeth into the tube, with further angular deflection of the teeth. In this manner, a locked configuration can be provided for the tubes.
Leadbetter, U.S. Pat. No. 2,831,711 issued Apr. 22, 1958, discloses the use of a connector sleeve designed to fit over and embrace ends of plastic pipes to be connected. Leadbetter also discloses the use of sealing materials to prevent escape of gas or liquid flowing through the interconnection joint.
The Leadbetter arrangement further includes a pair of fluid seals, with each seal being located in an end portion of the sleeve for operative engagement with the pipes inserted within the rings. The rings are formed from a resilient material, chemically inert with respect to the liquid or gas conveyed by the pipes. Each of the sealing rings is seated within an annular groove within the inner surface of the sleeve, and is sized so as to project inwardly beyond the inner sleeve surface. When a pipe length is inserted into one end of the connector, the pipe will engage and distort the sealing ring, so as to force the ring into tight contact with both the pipe length and the groove in which the ring is sealed. The ring is thereby prevented from being displaced by fluid pressure within the connector, while still providing for an effective sealing of the joint against fluid leakage.
For purposes of preventing longitudinal displacement of the pipe lengths from the connector, a locking arrangement is provided in each end portion of the sleeve, which permits insertion of the pipe but substantially prevents pipe withdrawal. More specifically, the locking arrangement includes a pair of split metallic rings having a generally frusto-conical shape, with a knife edge circumferentially extending around the periphery of the smaller end. Correspondingly, the inner surface of the connector sleeve is provided with a pair of outer annular grooves for removably receiving the split metallic rings. Each of the grooves forms a radially extending shoulder and an inclined surface extending from the end of the shoulder interiorly of the sleeve to the inner surface thereof. The shape of the grooves thereby conforms to the general shape of the locking rings. The depth of the grooves is such that the rings will be slightly spaced from groove surfaces, and extend beyond the sleeve inner surfaces. The respective knife edges are, therefore, directed angularly inwardly for engagement with the pipes. With the inclination of the knife edges in the direction of pipe insertion, the resiliency of the pipe material will permit the pipes to pass in the inserted direction. However, any reversal or withdrawing movement of the pipes will cause the knife edges to "bite" into the pipes around the pipe peripheries.
As the knife edge of each ring bites into the pipe, material is displaced therefrom in the form of shavings. The shavings will wedge themselves into the space between the ring and the adjacent groove surface, thereby assisting the locking action. In this manner, the pipes are locked within the connector sleeve.
Munger, U.S. Pat. No. 2,785,910 issued Mar. 19, 1957, discloses a molded pipe joint for use in coupling lengths of plastic and/or reinforced plastic pipe. More specifically, Munger discloses a pipe coupling member having a centrally located inwardly extending annular flange against which an end portion of a pipe to be interconnected abuts. Outer faces of the flange are beveled inwardly so as to assist in centering the end portion of the pipe within the coupling. An annular groove is cut into the inner surface of the coupling between the flange and the coupling end. A bore connects the annular groove with the exterior of the coupling. Adhesive is pumped inwardly through the bore, and completely fills the annular space between the pipe end and the interior wall of the coupling.
An annular spring catch member is mounted within the annular groove. The member has a V-shaped cross section, and is positioned within the groove with one side flush with the bottom of the groove and the other side extending diagonally inwardly toward the center of the coupling member. A wire is confined between the sides of the V-shaped member adjacent the pointed end, so as to urge the sides toward their extended relation. The inwardly extending side of the V-shaped member is notched so as to provide a series of inwardly extending catch fingers which bite into the surface of the end portion of the pipe, so as to prevent withdrawal once the pipe is inserted into the coupling. The fingers are also disclosed as assisting and centering the pipe end within the coupling. A similar arrangement is disclosed for use with an elbow-type interconnection of pipes.
Graham, U.S. Pat. No. 3,976,314 issued Aug. 24, 1976, discloses a coupler arrangement for ductile or deformable tubing. In one embodiment disclosed in the Graham arrangement, a T-coupler includes three ports, each adapted to receive a tube. Inserted within each port is a ferrule having a cylindrical configuration and composed of a stiff material, such as brass or similar metal. The inner end of each ferrule is provided with a radially-inward flaring circumferential lip. A radially-outward flaring circumferential lip is provided at the outer ferrule end.
The ferrule is inserted into the port and is sized so as to provide a friction fit with the walls of the coupler body. An adhesive can be provided on the outside surface of the ferrule and the inside surface of the port walls. Each of the ports includes an annular and enlarged diameter portion. The diameter of the ferrule corresponds to that of the ports, except for the outwardly extending lip. The lip fits within the enlarged annular portion of the port, and prevents further entry of the ferrule into the coupler body. The outwardly flaring lip bites into the wall of the port, so that the ferrule cannot be easily removed from the coupler body. After the ferrule has been inserted within the port, the tube is inserted through the ferrule until the end projects past the inwardly flaring lip. The tube projection is arrested by the reduced diameter of the internal passageway of the T-coupler.
The inwardly flaring lip will bite into the tubing as the tubing is inserted within the port. The lip is at an angle of slightly less than 90.degree. to the main part of the ferrule body, so that the tube is firmly locked within the port and axial movement of the tube out of the port is prevented. The ferrule provides for locking of the tube within the coupler, and also provides a fluid seal for purposes of preventing escape of fluid passing through the tubes and the coupler assembly. The seal is provided by the friction fit between the ferrule and the port walls, as well as the result of the biting action of the inwardly flaring lip circumferentially around the tubing.
Nordgren et al., U.S. Pat. No. 4,676,530 issued June 30, 1987, discloses a relatively complex coupling assembly for use in fluid flow systems. More specifically, Nordgren et al. discloses a fluid flow conduit having one end comprising a luer or tapered male slip fit connector, which is connected to a press fitted coupling assembly. The coupling assembly includes an annular collar having an internally threaded bore on its inner wall. The collar is provided with knurling on the outer periphery so as to facilitate manual threading of the collar to a correspondingly threaded end of a second female luer fluid flow conduit.
Positioned about the inlet end of the internally threaded bore is an annular groove in which the outer periphery of an annular disc type locking washer can be snap fitted so as to form a sliding fit between the washer and the groove. Depending upon the respective diameters of the groove and the washer, these elements can be relatively rotatable with respect to each other. The annular collar can draw the female luer connector onto the tapered male connector until the tapered surfaces of the male connector and the female luer connector are in an interference fit with each other.
The coupling arrangement also includes a cap device utilized as a dust cover, and also as a depth gauge to assure that the annular collar is axially aligned. The locking disc is engaged on the male luer with sufficient force so that both a threaded connection and an interference fit with the female luer are obtained. The annular washer can be shaped with a generally circular outer periphery, and sized so that it can be snap fitted into the groove on the inner wall of the annular collar. The washer can also be shaped so as to form an arc in cross-section, or a segment of a spherical surface in which the inner periphery is bowed with respect to the outer periphery. The inner periphery can define an opening in the disc type locking washer having a diameter or being sized so that the opening will be less than the root diameter of the tapered male connector.
The washer can be mounted rotatably in the groove so that it is transverse to the longitudinal line of the tapered male connector, with the bow facing towards the outlet end of the threaded bore of the annular collar. In this position, the coupling device is allowed to slide about the tapered male connector during assembly, and the locking washer is allowed to be moved longitudinally along the diameter thereof until the edges of the inner periphery engage and anchor the coupling device onto the male connector.
Nordgren et al. further discloses the notching of the inner periphery edge for the locking washer. Various notching arrangements are illustrated in the Nordgren et al. patent. The purpose of the notching is to provide sufficient resilience so that the locking member can engage the tapered male connector. After the locking washer is forced down on the tapered connector, back pressure against the notches will cause the same to bite deeper into the tapered connector in opposition to any potential separating force.
The foregoing describes only several of many arrangements employed for interconnecting pipes, pipe fittings, tubes and similar structures. As is apparent from the foregoing, many of these devices are relatively complex. In addition, a number of devices require substantial "process" to provide the interconnections, such as the application of electrical current within the Durkin device. Still other devices require particular structural configurations (such as inner grooves and the like) within the pipes and pipe fitting elements to be connected.